1. Field of the Invention
The present invention relates generally to wellhead blowout preventors, and more particularly to systems and methods for closing the rams of a blowout preventor.
2. Description of the Related Art
Blowout preventors are a part of wellhead assemblies associated with drilling and workover of subterranean wells, and in particular to hydrocarbon subterranean wells. Some blowout preventors seal across as central bore of the wellhead assembly, either around a tubular member that extends through the wellhead assembly, or across an open central bore where no tubular member extends through the wellhead assembly. For example, during drilling operations, the drill string is sealed to prevent damage to the well and associated equipment. The blowout preventor can be used to control unexpected well bore spikes to form a tight seal around the drill string until the well bore pressure can be returned to normal operating levels. The blowout preventor can also be used to seal around the drill pipe during stripping operations when the drill pipe is pulled from the wellbore. In a pumping production wellhead assembly, the blowout preventor may be configured to seal against a polished rod or a tubular member, if present. In other applications, a blowout preventor can be used to grip and hold, or to shear through, a tubular member that extends through the wellhead assembly.
In current blowout preventors, opposing rams move radially across the central bore and have faces that meet and seal across the central bore. Blind blowout preventor rams seal against each other across the central bore when no vertical tubular member is in place. The rams can be hydraulically actuated or can be moved with a hand crank or other mechanical or manual means. These current blowout preventors can be large and cumbersome due to the radial bores that extend outward on opposite sides of the blowout preventors for housing the radially moving rams and the ram actuation means.